Modulating system



Dec. 27, 1927. 1,654,285

c. LE G. FORTESCUE MODULATING SYSTEM Filed Oct. 25, 1921 INVENTOR Char/6.51:6. fEr/esaue.

A'TTORNEY Flt ill

Patented Dec. 27, 1927- PATENT OFFICE.

UNITED STATES CHARLES LE G. FORTESCUE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC 8:, MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

MODULA'IING SYSTEM.

My invention relates to wireless telegaphy and more particularly to means for controlling the power output of a trans mitting antenna system.

One of the objects of my invention is to neutralize the coupling between the supply circuit and the antenna circuit to prevent the transfer of energy therebetweeu.

A further object is to avoid all arcing between the contact points of the sending lrey.

A still further object to provide means for quickly absorbing the residual energy stored in the radiating circuit by causing the residual oscillations to set up a branchto-branch current in a multipie-branch antonna.

My invention consists in the methods and apparatus described in the following detailed description and illustrated in the uc-,

coiupanying drawing, wherein Figure l is a digrammatic view of an en1- bodiment of my invention en'lploying a common form of antenna, and

Fig. '2 is a sin'iilar view of a modification employing, a multiple-branch antenna in accordance with my invention.

In the system shown in Fig. 1, I provide a high-frequency source 3, which is connected to the primary coil 4 of a coupling transformer having a loosely coupled. secondary coil 5, which is included in an antenna circuit GI Connectedv in shuut relation to the primary coil 4 is a closely coupled, oppositely wound tertiary coil 7 including in circuit therewith a mntrolling hey it and a resistor 9.

By virtue of the arrangcincnt just dcscribed, power is supplied to the antenna circuit (3 when the key 8 is open. When the hey is closed, current flows through the primary and tertiary coils inopposite directions, thereby substantially neutralizing the coupling of these coils to the secondary coil 5, and the energy of the source 3 is absorbed by the resistor 9 which may be of such value as to maintain a substantially constant load upon the source. WVhen the key is again opened, there is no tendency to arc, as the secondary circuit begins at once to deprive the tertiary circuit of its energy.

Under certain circumstances, it may be found advantageous to include a capacitive rcactance in, the primary or tertiary circuit in order to neutralize the leakage in ductanco of the system, as indicated at 10 and. ll in F l.

In Fig. 2, I have shown similar system, in which the usual antemia circuit (3 has been replaced by a. multipledn'anch antenna circuit 12 including;- two adjacent antennae l3 and 14:. The antennae l3 and 1..1: are shown as commising alternate wires of single antenna construction 15, said alternate wires being connected, in two groups, to antenna loads 16 and 17, respectively. 7011- nected to the ends of the antenna leads is a balancing coil 18 having); its mid-point con nected to ground through the secondary coupling coil.

The antenna leads 16 and 17 may include tuning coils l5) and 20, respectively, whereby the antennae maybe timed to the frequency of the source 3. lileans are provided, also, as by making the tuning coil E20 larger than the tuning, coil 19 and inserting acompcnsat-ing condenser 21, whereby the time constant of one of the antenme is made la r than that of the other for a purpose which will appear hereinafter.

In imeration, the switch 8 is manipulated. as in the system shown in F lg. 1. During t :ansmission of signal impulses, the current divides equally between the two halves of the balancing coil 18, and energy is trans-- mitted from the two antennae operating: in unison. When the energy of the sourro is diverted from the secondary coupling coil 5, the residual stored cum-try in the antenna circuits causes the oscillations to cmitinue for a few cyr. as, dependent upon the time constant of the system.

In order to increase the rate at which the oscillations will decrease after the in tcrruption, of the source ofsupply lo the antennas, the system so designed that one antenna has a larger time constant than the other, whereby circulating currents are established in the circuit including the capacitance between the two antenna, the tuning coil 19, the balancing," coil l8, the tuning coil 20 and the condenser 21. The circuit just mentioned is designed to have a natural period corresponding to the fre quency of the source 3, whereby local. oscillations will be set up therein which will quickly absorb the stored energy without causing any sparking at the switch 8.

While I have described certain forms of my invention in detail, and while I have pointed out certain of the most obvious principles and purposes thereof, I do not intend that the language employed in the following claimsshallbe limited to the precise features described, but I intend that the claims shall be construed to cover all combinations which are fairly included in the language thereof, when read in view of the prior art regardless of the details and functions mentioned in the description or illustrated in the drawing.

I claim as my invention 1. In combination 'with a transformer having an auxiliary demagnetizing winding, an antenna system, said transformer constituting a loose coupling for supplying energy to said antenna, a load for said auxiliary winding, and means for transferring energy from said antenna system to said load byvdemagnetizing said driver transformer.

2. A couplingsystem comprising a pri mary induction coil, a secondary induction coil, a tertiary induction coil, the primary and tertiary coils being relativelytightly coupled and the secondary coil'being relatively-loosely coupled to the primary coil, the tertiar coil being Wound to oppose the effect of tie primarycoil on the secondary coil, means for controlling the flow of cur rent through the tertiary coil, and a condensive ireactor-in circuit with the tertiary coil to resonate with the leakage inductance of the system. v

3. A coupling system comprising a primary inductance coil, a secondary induc tion coil, :a tertiary induction coil, the primary and 'tertiary coils being relatively tightly coupledand the secondary coil being relatively-loosely coupled to said primary coil, the tertiary coil being Wound to oppose .the effect of the primary coil on the secondary coil, means for cont-rolling the flow of current through the tertiary coil, and a resistance device and a capacitance device in circuit with the tertiary coil, said capacitance device being of such size as to resonate with the leakage inductance of the system.

. 4. A sending system comprising a multiple-branch radiating circuit including an antenna, means for. supplying current to the multiple-branch circuit, and means for modulating saidcurrent, said radiating circuitincluding means for causing residual antenna-charges to set up a brach-to-branch current.

5. A sending system comprising a source of high-frequency oscillations, a multiple- ,branch antenna coupled thereto, an inductance dev1ce1n each branch, and means for controlling the current supplied to the multiple antenna from the high-frequency source, said antenna including means whereby a hranch-to-bianch current is set up when the energy supplied to said antenna by the high-frequency source is reduced.

6. A sending system comprising a continuous-wave source of high-frequency oscillations, a multiple-branch antenna cou- "pled thereto, means for controlling the current supplied to the multiplc-brancli anten- 11a, and means for causing residual charges to set up current-flow in a branch-to-hranch circuit.

7. A. sending system comprising a continuous-wave source of high frequency oscillations, a primary induction coil energized therefrom, a secondary induction coil relatively-loosely coupled to said primacy coil. a tertiary induction coil rclati\'el .'-tightly coupled to the primary coil, the tertiary coil being so wound as to oppose the cll'cct of the primary coil on the secondary coil, and a multiple-branch antenna energized from said secondary coil and including a resonant branch-to-branch circuit.

8. The combination with a pair of antenna-to-ground circuits having different time constants, of means for energizing said circuits from a common som-ce, and means for providing a tuned antenna-to-antenna circuit for increasing the damping of the circuits with respect to said common energizing means. v

9. A wireless transmitting system including two antennae, antenna-leads connected thereto, an impedance device joining said leads, a ground connection from an intermediate point of said. impedance dcvicc, means associated with said ground connection for energizing said antennae for radiation in unison, means for tuning the antenna-to-ground and antenna-to-antenna circuits, and means for causing one antennato-ground circuit to have adillerent time. constant than the other.

10. The combination with a pair of antennae and a source of high-frequency energy, of means for causing said cncr;: to divide substantially equally between said antenme during transmission of signal impulses, means for diverting the energy of said source from said antennic, and means for causing a time lag of the l't't-illllllll oscll la'tions in one antenna with respect to those in the other, and means for providing an antenna-to-antenna circuit effective to circulate local currents resulting from said time lag.

1.1. A wireless signaling system including an antenna-to-ground circuit and a loop circuit associated therewith, said loop circuit including two branches tuned to the signaling frequency and having difi'ercnt time constants, saidloop circuit, as a whole. being also tuned to the signaling frequency.

12. In a radio-transmitting system, the

ltlll combination with a continuou -Wave source, oi? a pair of oppositely-wound and inductively coupled coils connected thereto, means for varying the energy in one of said coils whereby the inagi'ietic iill'iK correspondiin jgly varied, an antenna system coupled to said coils and means included in said antenna system and providing a local circuit tuned to the frequency of said source and so disposed to carry circulatii'ig currents only upon a change in the amount oit energy supplied to said antenna system.

13. in a radiotransmitting system, the combination with a continuous-uuive source, oi? an antenna system coupled. thereto, means for causing a change in. the amount elf energy supplied to said antenna, system, and means ii'icluded in said ai'itenna system and providinga local circuit tuned to the tirequeney of said source and so disposed as to carry circulating currents only upon a change in the amount of energy supplied to said antenna system. i

141-. The combination with a high-frequency supply circuit, of a pair oi? shunt circuits iiiiciudin z; oppositely-wound transformer coils connected to said supply cir cuit, condensiye rcactance means in one or more of said circuits for neutralizing the inductive reactance therein, a tuned secondary circuit in inductive relation to said coils, and means for varying the energy supplied to said secondary circuit, said means including means for varying the relative magnet" izing eiiects of said. coils and means for imiiutaiuiiiig a siiihstantiaily constant total load on said supply circuit.

In testimony whereof, I have hereunto subscribed my name this 18th day oi" ()cto" her, 1921.

CHARLES LE G. FORTESCUE. 

